Common knowledge has it that the resolution of the mkI version of the EF 400 mm f/2.8 L was somewhat lacking. Being the happy owner of this lens I am sure that subsequent models are sharper, but finally decided that I had better test whether I was better of shooting with my EF 300 mm f/2.8 L IS coupled with a tele converter. Sorry for the borring brinck wall test

So, it appears that it still makes sense to log the 6 kg lens rather then the feather weight 2.5 kg 300 mm.

Here are some shots from the vintage (UG0304 = 1992) lens taken this past weekend in Dyrehaven just north of Copenhagen